1. Field of the Invention
The present invention is in the technical field of electronic alarms. More particularly, the present invention is in the technical field of silent electronic alarms.
2. Description of the Related Art
The use of silent electronic alarms is known in the prior art. More specifically, silent electronic alarms heretofore devised and utilized for the purpose of alerting one person without disturbing others are known to consist basically of familiar structural configurations. Devices intended for the deaf to elicit the attention of the user have been known; they tend to be complicated and awkward. In U.S. Pat. No. 2,517,368, Wisely describes a system where a time controlled mechanism is connected to the speaker coils of the hearing aid so that at a predetermine time the speaker coil will induce a tactile sensation in the ear. More recently, U.S. Pat. No. 4,821,247, Grooms describes in-the-ear and on-the-ear alarm devices. Furthermore, U.S. Pat. No. 5,867,105, Hajel discloses a warning system with sensors that detect smoke and transmit the triggering signal to a device worn on the person. Such device must hold the electronics for the receiving unit plus light emitting devices. Such devices alert the user but are bulky, uncomfortable and may fall off the ear rendering the device useless.
Another approach has been a vibratory system that rests under the pillow or near the sleeper. In U.S. Pat. No. 4,093,944, Muncheryan discloses a system for transmitting a recurrent, pulsative motion through the pillow in close proximity to the head of the sleeper and a more refine device is introduce by Chen in U.S. Pat. No. 5,144,600. Clearly such devices are bulky and required prolonged and strong vibrations to be imparted to the sleeper. Such a device produces vibrations throughout the whole bed as to not only wake the user but anyone in the bed and produces audible sounds from the strong vibrations, thus rendering the device useless as a silent alarm and as a system for only alerting one person without disturbing others.
In recent years, miniaturization of electronic parts has spurred the granting of patents of wristwatch configurations. In U.S. Pat. No. 5,289,452, Sakamoto et al. describes an electronic analog timepiece. It includes the plurality of time keeping indicators and the use of integrated circuitry in timekeeping wristwatch. Silent alarm wristwatch soon followed. In U.S. Pub. No. US 2003/0117272 A1, Fegley et al. describe a silent alarm device having a timekeeping mechanism, a wireless data transmitter and a receiving device which is secured to the user. At a predetermined time, a signal is transmitted to the silent alarm device to provide a tactile alarm. There is power saving strategies to increase the life of the battery. Entner et al. introduce a device in U.S. Pat. No. 5,282,181 where a motor having a rotation axis perpendicular to the bottom surface of the watch and bears an eccentric weight to generate a vibration or shaking of the device. In another embodiment of this patent, the bottom surface is a flexible membrane and a protrusion or bump in contact with the bottom membrane is driven to rotate to generate a tactile sensation. Another embodiment of this patent employs a plunger device that delivers a blow to the wearer's arm as the tactile alarm. Clearly this device imparts an awkward sensation to the user by the plunger, and is mechanically complicated and prone to outside atmospheric condition such as water damage.
A similar device is described in U.S. Pub. No. US 2007/0216537 A1, Park describes a wrist watch device coupled through radio signals to an alarm clock and emergency sensors. When activated a radio signal is transmitted to the device worn by the user and an electrical shock is issued to awaken a sleeper along with mechanical vibrations. Such a device makes a user uncomfortable to the idea of being shock, thus making it unsuited for wearing comfortably on the person. In U.S. Pat. No. 5,023,853, Kawata et al. Discloses a device that alerts the user through the use of an ultrasonic wave motor to turn an eccentric weight producing a vibratory sensation throughout the device. By vibrating the whole apparatus an audible sound is produced by the displacement of the eccentric weight inside the device. Berman et al. introduced a battery recharge system in U.S. Pat. No. 5,764,594.
These prior art silent alarms have been less than satisfactory. The energy required for vibrational stimulation is great. There have been some attempts at reducing the amount of energy used by these devices such as battery chargers and specialized circuits to control the amount of energy used, but they lack the effectiveness to produce noticeable results. Furthermore, devices described above that stimulate the skin through electrodes or tactical stimuli give an uncomfortable feeling. Further, there has been very little attempt at reducing the level of sound produced by the vibrating element. In the case of a sleeping or distracted user a silent alarm fail to show effectively that the systems will not draw attention from other especially if a vibrating mechanism is used. Further, the practical applications mentioned in the above-described references are limited to waking a sleeping person, or attracting attention of a person that is impaired such as blind or hard of hearing, or where emergency signals need to be communicated. Very little emphasis been directed to study aids for examination using such devices in the prior art.